Variable-pitch propeller



May 17, 1949. H. oBRi'sT 2,470,517

VARIABLE- PITC'I'i'hPRGrELpER Filed March 27, 1945 v A'2 sheets-sheet 1Fig.; I I

Inu encor Heinrich Obrs:

BQ @Mfgy@ May 17, 19495 H. Q qfmsr VARIABLE FITCHV PROPELLBR :2Sheets-Sheet 2 Filed March 27, 41945 l INV lnuenor Heinrich ObriscY ubem.

Patented May 17, 1949 2,470,517 VARIABLE-BITCH PnopnLLEn HeinrichOhrist.. Zurich, Switzerland, assigner te Escher Wyss.

Macliinenfabriken 'Aktiengesellf .scllaftfznriclp Switzerland, acorporation ef Switzerland nrrlieationMaren 27, 1945, Serial No. 585.933.In Switzerland Avril 27 1.94.4.

2 Claims. l

This invention relates to a variable-pitch propeller for ships, aircraftand centrifugal inachir-les,l provided with cranksi or varyingthe pitchofthe propeller blades, each of the cranks being .formed integral withits correlated blade root.

To simplifythe assembly of propellers of this kind it has already beenproposed to split the hub into two parts in the planeI through vthe axisof rotationei the blade root or in aplane parallel tliereto Snclisplitting oi the nnb eanreadilv be adopted where srnalpler Propellersand relatively Small 'fililllslisll' QQllQelnfQ; .blll is, HQ lOllgel.$1.111"- able as soon large` bearing forces and adjustine nave to 'bedealt.-witli2 then tbe available space. proves tee sinall for datingsirdieientl'vr strong` connecting. rnernbers-V `In an endeavoiirtoovercorne this difficulty a variable-.pitch propeller according to tbepresent invention vtbe. rnernbers which serve sirnnltaneonslv-as bladeroots and adjusting cranks can be inserted into. the iinsplit hubthrough .open-y ings provided therein and having at least two recessesprojecting radially outwards, said ineinbers;v alter having` beenadlllsted relatively to said recess, bei-ns held `fast in tbe propellerliiib in a radial direction by at least two projections pro: vided thesernernbers and resting asa/inst the inner surface of thevhgb.

The. accompanying drawing snowsbv wav ei example construetionalernbedinien o ftlre. slibject matter of` they invention. ln drawing:

Fis. 1 snows an .axial lengitdinal section through part4 ci avariablefpitcn .snip propeller, in which eachblade. is bolted to itsroot, the latter being supported inthe propeller hub.

Fig. 2 shows a section on the line'IIffII of Fig. 1,

Fig. 3 shows a plan v ievv of the propeller hub in which the blades haveso far not been inserted, bvphenated lines indieat.inel an adjustingcrank in the position in which it would lock its correlated blade in theradial direction.

Fig. 4 shows a plan View of a blade root together with its adjustingcrank which forms an integral part thereof, this member beingillustrated. in the approximate position into which it has to be broughtfor insertion in the hub when the latter is in the position shown inFig. 3.

r'is- E shows bow a niernber consistingl ei a blade root and anadjusting crank can be inserted in the hub.

Fig. 6 shows the same as Fig. 5 for the case Where the propeller bladeis formed integral With its root and with the adjusting crank.

(C1. IWI-160,24)

Fig. 'I snows a section on tire line Vllwlll of Fig. e, intermediate.pieces being also. indicated which. placed in grooves in the propellernnb after tlie blade root been inserted intnis nnb- Fis. a snows largerscale tbe ineens which areprovided at tire. points,` wneretne bladeroots are supported the propeller hub.

Eig. 9 snows .an axial' longit.. dinal section through part or a.rnrtber ernbodnnent ci tlie invention; and

Fig. 10 is a section gn the line oi Fig., 9..

.In Fles.. l to. d is sliovvna three-blade variable pitcn snipprepellertne blades. l er wnicn areL detaeliablv seenrled to their roots2 bv of bolts. 4- The blade rootsz .rncvablv supported the propeller 3bv rneans or a .il at tbe inner end ci the root and by a journal lllwlneli is located just within the periphery` ci tbe lnrb and each oftbeno is. iorrned. intearalwitha cerrelatedadjustine t to tlie4respective root between said trennten, Sand saidiojirnal In. The variouscranksV operatively ecnnected to adjusting mechanism lsnown per se andwhich llasnotlring todo with tlre al features of the invention sctntit's nl trier shown. in the drawingy nor. liereinaiter described:

To ensnre that .the root?, after tbe correlated blade l has been movedinto tbe position, is locked in the radial direction in the hllb t'. twoprojections 6 arranged opposite te one.`

another are provided on blade root 2.. these projections being termedlikewiseintesral with the root this embodiment cf tneinvention. lierinserting in tne nnb .3. in the manner indicated in Fis.. 5 the variousniernbers composed each of a root 2.. an adjusting eranlr 5 and twoprojections 6. bores 'l havingeaen two recesses 8 projecting radiallyoutwards are provided in the linbs 3. (Figs. 3 and 5). The crossvsection of the re: cessesne .is somewhat greater-than thatcf tbeprojections 5- The operation of mounting a blade-roet;` in the nnb .iscarried out as iollows. The roet tisse nositiened lsee, for example-Fie.el that itsbavoiiet lugs 6 `can be introduced `t.n.reiltl.1 reeessesllfAlter snenintroddetion and the insertion of tbe trnnnicn ilintotnebearing` provided tbererer near tbe center or triennio, trie.root and its attaelied adjusting crank are abont s so that the lugs 6are displaced from the recesses 8 through which they entered, and engagean arcuate seat formed therefor on the internal face of the hub. Theposition which results is illustrated in dotted lines in Figure 3. Inthis position the projections 6 act as a lock with regard to thecentrifugal forces exerted on the correlated blade I in that they restdirectly against the inner surface of the hub 3. In the radial directionthe root 2 that has been inserted into the hub 3 is supported near itsinner end by trunnion 9 and near its outer end its journal I0 (see Fig.2) and is held between inserted pieces 8' which function as bearings andwhich are inserted into the recesses 8 after the root is in position.

Thus, in the embodiment herein described the usual well-tried method ofsupporting the blade roots 2 in the hub 3 is possible; furthermore anextremely reliable connection between root 2 and adjusting crank issecured, and thirdly an easy insertion of the blade roots together withthe adjusting cranks in the hub 3 is possible, and this without thenecessity of providing in the hub particularly large bores which wouldreduce its strength.

In Fig. 8 is illustrated on a larger scale how the sealing of thepropeller root 2 is attained at the point where it is inserted in thepropeller hub 3. In this Fig. 8 the numeral I I denotes a ring formingthe sealing member proper and I2 is a disc connected to the blade root 2in a manner permitting of its being unscrewed. The sealing ring I I alsorests against a metallic ring I3, which a number of springs I4 forceagainst ring II, so that the external surfaces of the latter beartightly against hub 3 and disc I2.

As illustrated in Fig. 6 the invention is also suited for applicationwhen the propeller blade Ill and the root I5 are formed integral withthe adjusting crank I6 and with the projection Il' serving as lockingmeans. In this case also intermediate pieces I8 are placed in grooves I91 of the hub I9 after the parts I4, I5, I6 and I1 have been inserted,the cross section of said intermediate pieces I3 being somewhat smallerthan the cross section of the grooves I 91 in the propeller hub I 9which have to be provided for the introduction of the projections I1.These pieces I 8 act also as bearing surfaces for the blade root I5.

In both the embodiments above described the bayonet locking lugs 6(Figs. 1-5) and I'I (Figs. 6 and 7) are formed integrally with the root.As will be noted from an examination of the abovementioned figures thelugs are located adjacent the inward end of the journal II] and projectradially outward beyond the surface of said journal to engage the seatformed on the interior surface of the hub. From this last circumstanceit follows that the bayonet locking lugs are loaded unidirectionally.They simply resist forces which tend to move the root outward in aradial direction relatively to the hub. Any arrangement which willresist such unidirectional force will meet the requirements, andaccordingly simple alternative structures may readily be contrived. Onevery desirable arrangement is shown in Figures 9 and 10.

In these figures a shoulder or iiange is formed on the root 22 at theinward end of the journal 2 I. A sleeve-like bushing or bearing element24 lls the annular space between the journal 2| and the margin of thelarger aperture in the hub 23. With such an arrangement it isconveniently possible to use four bayonet lugs 25 4 to resist thecentrifugal tendency of the root 22 and the blade 26. The use of fourbayonet lugs entails the use of four recesses 21. The lugs are formeddirectly on the bearing element 24.

After the bearing element has been placed and turned to engage thelocking lugs it is fixed in position by a stake 28.

Thus it will be seen that while it is characteristic of the inventionthat the bayonet locking lugs are sustained by the root againstdisplacement in an axial direction toward the trunnion end of the root,this is really all that is strictly required. Consequently, while it ispossible and often convenient to form these lugs integrally with theroot, it is not strictly essential that they be so formed. In cases suchas that illustrated in Figs. 9 and 10 it is preferred to sustain them sothat they react against the root but are not integral therewith.

What is claimed is:

l. In a variable pitch propeller, the combina tion of a hollow hubhaving its peripheral portion constructed as a continuous un-splitshell, said hub having near its axis a plurality of radially disposedbearings one for each blade root and a plurality of generally circularapertures in said peripheral portion and respectively centered on theaxes of corresponding radially disposed bear ings, each aperture havingopposed notches for the passage of bayonet locking lugs; a plurality ofblades each having a root, each of Said roots having at its inner end atrunnion adapted to work in a corresponding radially disposed bearm ingand having near its outer end a journal the diameter or" which isslightly less than that of a corresponding one of said apertures, eachroot having between said journal and trunnio;A an ine tegral arm radialto the axis of the root; bayonet locking lugs sustained by respectiveroots against relative axial displacement at least in the directiontoward the trunnion end thereof, said lugs having connection with andprojecting radially outward beyond the journal adjacent the inward endthereof, said lugs being dimensioned to enter said shell through saidnotches and engage the inner surface of the shell; and bearing-forminginterposed between each journal and the surrounding portion of saidshell.

2. The combination dened in claim 1 in which the root is formed with ashoulder defining the inner end of the journal, and the bearing-formingmeans is in the form of a ring which encircles the journal, seatsagainst said shoulder, lls the annular interval between the journal andthe margin of the corresponding aperture, and carries the bayonetlocking lugs.

HEINRICH OBRIST.

REFERENCES CITED wing references are of record in the patent:

NETE@ STATES PEITENTS

